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SubjectRe: [linux-sunxi] [PATCH 3/6] drm/sun4i: dsi: Add bridge support
On Fri, Mar 15, 2019 at 02:32:55PM +0100, Paul Kocialkowski wrote:
> Hi,
>
> On Fri, 2019-03-15 at 18:38 +0530, Jagan Teki wrote:
> > Some display panels would come up with a non-DSI output which
> > can have an option to connect DSI interface by means of bridge
> > convertor.
> >
> > This DSI to non-DSI bridge convertor would require a bridge
> > driver that would communicate the DSI controller for bridge
> > functionalities.
> >
> > So, add support for bridge functionalities in Allwinner DSI
> > controller.
>
> See a few comments below.
>
> > Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> > ---
> > drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 65 +++++++++++++++++++-------
> > drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h | 1 +
> > 2 files changed, 49 insertions(+), 17 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> > index 0960b96b62cc..64d74313b842 100644
> > --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> > +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> > @@ -781,6 +781,9 @@ static void sun6i_dsi_encoder_enable(struct drm_encoder *encoder)
> > if (!IS_ERR(dsi->panel))
> > drm_panel_prepare(dsi->panel);
> >
> > + if (!IS_ERR(dsi->bridge))
> > + drm_bridge_pre_enable(dsi->bridge);
> > +
> > /*
> > * FIXME: This should be moved after the switch to HS mode.
> > *
> > @@ -796,6 +799,9 @@ static void sun6i_dsi_encoder_enable(struct drm_encoder *encoder)
> > if (!IS_ERR(dsi->panel))
> > drm_panel_enable(dsi->panel);
> >
> > + if (!IS_ERR(dsi->bridge))
> > + drm_bridge_enable(dsi->bridge);
> > +
> > sun6i_dsi_start(dsi, DSI_START_HSC);
> >
> > udelay(1000);
> > @@ -812,6 +818,9 @@ static void sun6i_dsi_encoder_disable(struct drm_encoder *encoder)
> > if (!IS_ERR(dsi->panel)) {
> > drm_panel_disable(dsi->panel);
> > drm_panel_unprepare(dsi->panel);
> > + } else if (!IS_ERR(dsi->bridge)) {
> > + drm_bridge_disable(dsi->bridge);
> > + drm_bridge_post_disable(dsi->bridge);
> > }
> >
> > phy_power_off(dsi->dphy);
> > @@ -973,11 +982,16 @@ static int sun6i_dsi_attach(struct mipi_dsi_host *host,
> > struct sun6i_dsi *dsi = host_to_sun6i_dsi(host);
> >
> > dsi->device = device;
> > - dsi->panel = of_drm_find_panel(device->dev.of_node);
> > - if (IS_ERR(dsi->panel))
> > - return PTR_ERR(dsi->panel);
> >
> > - dev_info(host->dev, "Attached device %s\n", device->name);
> > + dsi->bridge = of_drm_find_bridge(device->dev.of_node);
> > + if (!dsi->bridge) {
>
> You are using IS_ERR to check that the bridge is alive in the changes
> above, but switch to checking that it's non-NULL at this point.
>
> Are both guaranteed to be interchangeable?

They aren't. Any ERR_PTR will be !NULL

> > + dsi->panel = of_drm_find_panel(device->dev.of_node);
> > + if (IS_ERR(dsi->panel))
> > + return PTR_ERR(dsi->panel);
> > + }
>
> You should probably use drm_of_find_panel_or_bridge instead of
> duplicating the logic here.

Or we can even use the drm_panel_bridge_add to simplify things.

Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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